Get the angle whose sine is float value argument in C#

To get the angle whose sine is a float value argument in C#, we use the MathF.Asin() method. This method returns the arcsine (inverse sine) of the specified number in radians. The input value must be between -1 and 1, otherwise the method returns NaN (Not a Number).

Syntax

Following is the syntax for MathF.Asin() method −

public static float Asin(float x)

Parameters

• x − A number representing a sine value. Must be between -1 and 1 inclusive.

Return Value

Returns the arcsine of the specified number in radians. If the input is outside the range [-1, 1], it returns NaN.

Using MathF.Asin() with Valid Input

Example

using System;
public class Demo {
    public static void Main() {
        float val1 = 0.1f;
        float val2 = 0.5f;
        float val3 = 1.0f;
        Console.WriteLine("Angle (val1) = " + (MathF.Asin(val1)));
        Console.WriteLine("Angle (val2) = " + (MathF.Asin(val2)));
        Console.WriteLine("Angle (val3) = " + (MathF.Asin(val3)));
    }
}

The output of the above code is −

Angle (val1) = 0.1001674
Angle (val2) = 0.5235988
Angle (val3) = 1.570796

Using MathF.Asin() with Invalid Input

Example

using System;
public class Demo {
    public static void Main() {
        float val1 = 1.2f;
        float val2 = 45.5f;
        float val3 = -2.0f;
        Console.WriteLine("Angle (val1) = " + (MathF.Asin(val1)));
        Console.WriteLine("Angle (val2) = " + (MathF.Asin(val2)));
        Console.WriteLine("Angle (val3) = " + (MathF.Asin(val3)));
    }
}

The output of the above code is −

Angle (val1) = NaN
Angle (val2) = NaN
Angle (val3) = NaN

Converting Radians to Degrees

Since MathF.Asin() returns the result in radians, you may need to convert it to degrees for better understanding −

Example

using System;
public class Demo {
    public static void Main() {
        float sineValue = 0.5f;
        float angleRadians = MathF.Asin(sineValue);
        float angleDegrees = angleRadians * (180.0f / MathF.PI);
        
        Console.WriteLine("Sine value: " + sineValue);
        Console.WriteLine("Angle in radians: " + angleRadians);
        Console.WriteLine("Angle in degrees: " + angleDegrees);
    }
}

The output of the above code is −

Sine value: 0.5
Angle in radians: 0.5235988
Angle in degrees: 30.00001

Conclusion

The MathF.Asin() method calculates the arcsine of a float value and returns the angle in radians. The input must be between -1 and 1; values outside this range return NaN. Convert the result to degrees by multiplying by 180/? if needed.